With popularization of the UMTS technology, various high-speed wireless applications become popular. Public demand for high-speed data services is growing. With the continued development of services and changes in users' application services, according to some survey results, about 30% of services are used in the family area, and about 35% of the services are used in companies, restaurants and other indoor scenarios. Therefore, the quality of indoor coverage will largely affect the experience of the users using the services, but in these scenarios, because the traditional macro base stations generally use the 2.1 GHz frequency band resources, the transmission loss and space loss are relatively large, and the capability of passing through the building wall is relatively weak, which may cause poor indoor coverage quality. Also for hot spots, such as business districts, subway stations and other areas where there are a large number of people and the demand for communications is very large, the capacity is also prone to be limited due to reasons such as site selection of the macro base stations and the costs, thus affecting the user service experience. In view of these situations, the micro base station solution is introduced to deal with this type of scenarios, on the one hand to supplement the coverage of the macro base stations to improve the quality of indoor coverage and the user service experience, and on the other hand to shunt the services of the macro network to relieve the traffic pressure of the macro network.
The main features of the micro base station comprises low transmit power, small coverage, small size, and flexible application. Based on these features, with respect to the networking mode of the macro base station, there may be a large number of micro base stations in a local area. In the definition of measurement control in the 3GPP (The 3rd Generation Partnership Project) protocol, only a maximum of 31 neighbor cells can be carried. When there is a large number of micro base stations, the number of neighbor cells of a macro base station/micro base station is likely to exceed the restriction on the number of neighbor cells in the measurement control, especially, the number of neighbor micro base stations under the jurisdiction of a macro base station may far exceed the restriction on the number of neighbor cells, therefore when sending the measurement control, it is unable to determine the appropriate neighbor cell, leading to a decreased mobility and even a call drop. To address this issue, in R8 (Release 8) and later versions, the 3GPP introduced some strategies, such as the CSG (Closed Subscriber Group) cell, the UE (User Equipment) assisted ANR Logging Measurement reporting and so on, but the problem still exists in hundreds of millions of UEs prior to the R8 versions in the existing network.